In this paper, we investigated the entanglement dynamics between two two-level natural or artificial atoms interacting with a thermal one-mode field of lossless cavity taking into account the direct dipole-dipole and Ising coupling. We obtained the exact solution for time-dependent density matrix and calculated atom-atom negativity. The results showed that for dipole-uncoupled atoms and resonant atoms-field interaction the entanglement greatly enhances with Ising coupling increasing. In contrast, for model with non-zero detuning the Ising coupling has almost no effect on the degree of entanglement. We also derived that for resonant interaction and dipole-coupled atoms the anti-Ferromagnetic coupling produces a slightly higher degree of entanglement in comparison with the Ferromagnetic coupling. For entangled initial atomic states we obtained that Ising coupling interaction has effect on entanglement behavior only for a model with large detuning values.
In this paper, we investigated the entanglement dynamics between two dipole-coupled qubits not-resonantly interacting with a thermal one-mode field of lossless cavity with Kerr media. We obtained the exact solution for time-dependent density matrix and calculated on its basis the qubit-qubit entanglement parameter – negativity. The results show that Kerr nonlinearity greatly affected the entanglement behavior. More interestingly, that for initial entangled qubits states Kerr media avoids the entanglement sudden death effect.
In this paper, we investigated the entanglement dynamics between two superconducting qubits interacting with a thermal one-mode field of lossless cavity with the Kerr media. We obtained the exact solution for time- dependent density matrix and calculated on its basis the qubi-qubit entanglement parameter-negativity. The results show that Kerr nonlinearity greatly affected the entanglement behaviour. More interestingly, that initial qubits coherence greatly enhances the degree of entanglement in the presence of the Kerr medium.
In this paper, we investigate entanglement between two qubits when they simultaneously not-resonantly interact with a single-mode thermal field through the degenerate two-photon transitions. We obtain the exact solution of the quantum Liouville equation for density matrix of the considered systems in the "dressed" states representation. On its basis the calculate the qubit-qubit reduced density matrix and negativity. We show that a slight detuning between the qubit transition frequency and the twice field frequency might cause high entanglement between the qubits.
In this paper, we have investigated the entanglement dynamics between two initially entangled qubits interacting with two independent thermal cavities modes in the framework of resonant double Jaynes-Cummings model. We obtain the exact solution for the model under consideration and derive the time dependence of the atom-atom negativity. Results reveal that for entangled atoms the initial atomic quantum correlations can partially restore its original values for a finite interval of time, even for relatively high cavity temperatures.
In this paper, we have investigated the entanglement dynamics between two identical two-level atoms in the framework of two-photon double Jaynes-Cummings model taking into account the detuning between atoms and twice cavities frequencies and Kerr nonlinearities in both cavities. We have carried out the temporal dependence of the atom-atom negativity for Bell’s initial entangled atomic states. The results show that these parameters have great impact on the amplitudes of the atom-atom entanglement oscillations and that presence of detuning and Kerr nonlinearity lead to stabilization of entanglement for all Bell-types initial atomic states. For a certain initial atomic entangled states, there is an entanglement sudden death effect between the two atoms. The detuning and Kerr medium in the cavities can prevent the undesirable entanglement sudden death from occurring.
We investigated the entanglement of a quantum system consisting of a Jaynes-Cummings atom, thermal lossless cavity and an isolated atom. The analytical expressions of the atom-atom negativity for separable, separable coherent and entangled initial atomic states were obtained. The influence of initial atomic coherence, detuning between the atomic transition frequency and the field frequency and direct dipole-dipole interaction on an atom- atom entanglement is examined. We showed that for a separable and separable coherent initial atomic states a detuning might cause high atom-atom entanglement in the presence of the dipole-dipole interaction even for thermal field with high intensity. We also obtained that for entangled initial atomic states a detuning causes a stabilization of an entanglement oscillations.
This paper studies the entanglement properties in a system of two dipole-coupled natural or artificial two-level atoms not-resonantly interacting with an intensive single-mode thermal field for coherent initial atomic states. The results show that the entanglement is weaken due to the initial atomic coherence for model with detuning in contrast to the model with resonant atom-field interaction. For non-dissipative model under consideration the detuning results also in decreasing of the atom-atom entanglement in time for separable initial atomic state and intensive cavity thermal field.
We considered a quantum model consisting of two effective two-level atoms interacting with a single-mode thermal cavity field through two-photon transitions. We explored the entanglement dynamics between two atoms, and studied the effect of the Stark shift on the entanglement. The results showed that for a separable initial atomic state the Stark shift enhances the amount of atom-atom entanglement induced by the thermal field. For entangled atomic state the Stark shift reduces the the atom-atom entanglement oscillations.
In this paper, we investigated the entanglement dynamics between two superconducting qubits in the framework of not-resonant double Jaynes-Cummings model taking into account the direct dipole-dipole interaction. We explored the dependence of the atom-atom entanglement on the strength of the dipole-dipole interaction and detuning. The results show these parameters affect the period of negativity oscillations but not the maximum value of entanglement in contrast to two-atom Jaynes-Cummings model with common cavity mode.
We have investigated the dynamics of entanglement of two identical qubits non-resonantly interacting with one mode of a thermal electromagnetic field in a lossless cavity in the presence of a direct dipole-dipole interaction. On the basis of the exact solution the evolution equation the negativity for qubits has been found. Numerical simulation of the negativity for various model parameters has been carried out. It has been shown that the interaction of qubits with the cavity thermal field can lead to their entanglement. It has been established that the detuning and dipole-dipole interaction of qubits can be used to manipulate and control the degree of their entanglement.
We investigated the entanglement between two qubits interacting with two independent modes of lossless resonators taking into account the dipole-dipole interaction. The model with different qubit-field couplings and detunings is under consideration. We derived the exact solution for considered model and investigated the dependence of the atom-atom entanglement on the strength of the dipole-dipole interaction and other parameters of the considered system. The results showed that the presence of a sufficiently large dipole-dipole interaction leads to stabilization of initial atom-atom entanglement.
An exact solution of the problem of two-atom one- and two-mode Jaynes-Cummings model with intensity- dependent coupling is presented. Asymptotic solutions for system state vectors are obtained in the approximation of large initial coherent fields. The atom-field entanglement is investigated on the basis of the reduced atomic entropy dynamics. The possibility of the system being initially in a pure disentangled state to revive into this state during the evolution process for both models is shown. Conditions and times of disentanglement are derived.
An exact solution of the problem of two two-level atoms with degenerate Raman two-photon transitions interacting with one-mode coherent or thermal radiation field in cavity is presented. Asymptotic solution for system state vector is obtained in the approximation of large initial coherent fields. The atom-field is investigated on the basis of the reduced atomic entropy dynamics. The possibility of the system being initially in a pure disentangled state to revive into this state during the evolution process is shown. Conditions and times of disentanglement are derived. The atom-atom entanglement is investigated with using negativity. The possibility of sudden death and birth of atom-atom entanglement is predicted for a coherent field with large mean photon numbers.
In this paper, we have investigated the entanglement dynamics between two initially entangled superconducting qubits in the framework of a double Jaynes-Cummings model with different atom-filed coupling constants and detunings taking into account the direct dipole-dipole interaction. We have carried out the dependence of the atom-atom entanglement on the strength of the dipole-dipole interaction and other parameters of the considered system such as the different coupling constants and the detunings. The results show these parameters have great impact on the amplitude and the period of the atom-atom entanglement evolution. In addition, the presence of sufficiently large dipole-dipole interaction leads to stabilization of entanglement for all Bell-types initial qubits states and different couplings and detunings.
The entanglement between two identical two-level atoms successively passing the thermal cavity has been investigated taking into account the detuning. The case when atoms are initially prepared in the Bell types entangled atomic states has been considered. It has been shown that for vacuum state of the cavity the presence of detuning leads to decreasing of the entanglement amplitude oscillations. We have also derived that for thermal field the increasing of the mean photon number leads to decreasing of the entanglement, but the entanglement increases as the detuning increases. For thermal field and small detuning we have established that the effect of sudden death and birth of entanglement takes place and that for large detuning such effect vanishes.
We investigated the entanglement dynamics in a quantum system consisting of three two-level atoms resonantly coupled to a single mode electromagnetic field. We considered the dynamics of the system under consideration for Fock and thermal initial cavity states. An explicit analytical solution of the system has been obtained and the entanglement has been studied with the help of the two-qubit negativity. It was also shown that for both initial cavity states the sudden death of two-qubit entanglement takes place.
We study the entanglement properties of a pair of two-level atoms going through a thermal cavity one after another. The initial joint states of two successive atoms that enter the cavity are coherent or entangled. Using the exact solution of density matrix evolution equation we calculated the negativity for different values of cavity mean photon numbers. We shown the possibility to save the initial atomic entanglement even for a thermal cavity field with relatively high temperature.
We have investigated the influence of dipole-dipole interaction and initial atomic coherence on atomic entanglement dynamics of two qubits. We have considered a model, in which only one atom couples to a quantum electromagnetic field in a cavity, since one of them can move around the cavity. We have shown that the entanglement arises for all pure atomic state even when both atoms are initially in the excited states. We have also derived that degree of entanglement is enhanced in the presence of the atomic coherence.
Squeezing for one- and two-mode two-atom Jaynes-Cummings model with intensity-dependent coupling has been investigated assuming the field to be initially in the coherent state. The time-dependent squeezing parameters have been calculated. The influence of the intensity of the cavity field and initial atomic state on the squeezing parameters has been analyzed.
In this paper we have investigated the atom-atom entanglement for degenerate two-photon Tavis-Cummings model with taking into account Stark shift and initial atomic coherence. Considering different initial coherent states we have derived that the atom-atom entanglement can be greatly increased or decreased due to the presence of the Stark shift. In addition, we have derived that the entanglement sudden death effect vanishes due to the presence of Stark shift for some initial states.
We have investigated the influence of dipole-dipole interaction and initial atomic coherence on dynamics of two-atom systems. We have considered a model, in which only one atom is trapped in a cavity, and the other one can be spatially moved freely outside the cavity. We have shown the possibility of disappearance of the entanglement sudden death effect in the presence of the dipole interaction of atoms. We have also derived that the initial atomic coherence can be used for effective control of the degree of the atom-atom entanglement.
The entanglement of two dipole-coupled superconducting flux qubits with degenerate and nondegenerate twophoton transitions interacting with one-mode or two-mode field in lossless cavity has been investigated. The influence of dipole-dipole interaction on the entanglement between two qubits for different initial atom-field entangled states has been considered. The results show that the entanglement between two artificial atoms can be increased by means of dipole-dipole interaction and for some initial states the entanglement sudden death effect can be weakened.
The entanglement of two dipole-coupled superconducting flux qubits with degenerate two-photon transitions
interacting with one-mode superconducting LC circuit has been investigated. The possibility of considerable
growth of atomic entanglement due atomic coherence and dipole-dipole interaction has been shown.
An exact solution of the problem of two two-level atoms with nondegenerate two-photon transitions and intensitydependent
coupling interacting with two-mode radiation field is presented. Asymptotic solution for system state
vector is obtained in the approximation of large initial coherent fields. The atom-field entanglement is investigated
on the basis of the reduced atomic entropy dynamics. The possibility of the system being initially in a pure
disentangled state to revive into this state during the evolution process is shown. Conditions and times of
disentanglement are derived.
The entanglement of two dipole-coupled atoms with nondegenerate two-photon transitions interacting with twomode
field in lossless cavity has been investigated. It shows that the entanglement is dependent on the initial
atomic states. The possibility of considerable growth of atomic entanglement due atomic coherence and dipoledipole
interaction is shown in the case of great mean values of thermal photons.
The entanglement between two identical two-level atoms successively passing thermal cavity and interacting with
one-mode thermal field through a degenerate two-photon process is investigated. It is shown that two atoms can
be entangled through such nonlinear interaction.
In this article the interaction of two nonidentical two-level atoms with one mode of the electromagnetic field has
been considered. The pure-state evolution of the atomic states for field initially in the coherent state and atoms
in the ground state has been investigated. The possibility of the maximally entangled states at the beginning of
the collapse time has been discussed.
The exact wave function is found in the work for the two-atom models with nondegenerate two-photon interaction
and nondegenerate raman interaction. The asymptotic solutions for system state vectors are obtained in the
approximation of strong field for considered models for different initial atom states and coherent field input.
The reduced entropy dynamics is described for various initial atomic states and coherent field input, some
conclusions about atom-field entanglement are made. We also show the possibility for the system being initially
in the pure nonentangled state to revive into this state during the evolution process for the two-atom model with
nondegenerate two-photon interaction and we obtain the times of such revivals.
The exact wave function and asymptotic expressions for the system state vectors under strong initial coherent
fields are found in the work for the two-atom models with nondegenerate two-photon interaction and nondegen-
erate Raman interaction. The atom-field entanglement is considered via linear entropy criterion. The system
revivals to unentangled states are shown to appear for both models. The disentanglement times are derived in
the work. The atom-atom entanglement induced by thermal noise is investigated for the both models.
KEYWORDS: Chemical species, Correlation function, Systems modeling, Photonics systems, Quantum information, Physics, Electromagnetism, Atrial fibrillation, Chemical elements, Complex systems
In this work we considered temporal behaviour of a two two-level atoms in a infinite-Q cavity with atom dissipation
for coherent and squeezed inputs. The analytic expressions for second-order correlation function and squeezing
parameters and amplitude-squeezing parameters are obtained on the basis of master equation solution. System
observables dynamics is investigated for coherent and squeezed initial field state for various system parameters values.
The entropy dynamics for three-level Ξ-type atom is investigated in the article. The analytic expressions for atomic
entropy are obtained in the work, as well as exact solutions for Schr&diaero;dinger equation for wave function. The
entanglement dynamics in the system is considered on the base of reduced entropy analysis.
In this work we considered temporal behavior of squeezing and amplitude-squared squeezing for a two two-level
atoms in a finite-Q cavity with atom dissipation. The analytic expressions for squeezing parameters are obtained
on the basis of master equation solution for coherent and squeezed input. Squeezing generation conditions are
considered for various dissipation parameters values and coherent and squeezed initial input.
The entanglement between two unidentical two-level atoms with different frequencies interacting with one-mode
thermal field in lossles cavity has been investigated. The role of detuning in this effect has been carried out.
The kinetics of the extended model of crystal doped by rare-earth ions in regime of anti-Stokes laser cooling
has been considered taking into account the collective radiation effects. The system of master equations for
impurities and pseudo-local phonons has been obtained. As would be expected, the collective radiation effects
causes an acceleration in relaxation depletion of the phohon mode and therefore an increase of crystal cooling
efficiency.
A nondegenerate two-photon Jaynes-Cummings model is investigated where the leakage of photon through the
cavity is taken into account. The effect of cavity damping on the mean photon number, atomic populations,
field statistics and both field and atomic squeezing is considered on the basis of master equation in dressed-state
approximation for initial coherent fields and excited atom.
The entanglement between two identical two-level atoms interacting with two mode thermal field through a nondegenerate two-photon process has been suggested. The role of detuning has been illustrated by the example of simple one-mode two-atom model.
The collective spontaneous radiation of the macroscopic system of V-type three-level atoms interacting with quantum electromagnetic field and coherent pumping field has been investigated on the basis of the Bogolubov's method of the elimination ofthe boson variables. The possibility of the subradiant and superradiant regimes in dependence of the pumping area has been established.
The dynamics of detuned two-level Jaynes-Cummings model with multiphoton transitions in the finite Q-cavity has been considered. The time evolution of the mean photon number and atomic populations has been investigated for various values of the model parameters. The type of field statistics and photon bunching/antibunching effects has been examined.
On the basis of the master equation for the density matrix the dynamics of the collective spontaneous radiation of two Λ - type three-level atoms interacting with two modes of quantum electromagnetic field in the damped cavity has been considered. The behaviour of the photon numbers in modes has been investigated in the case when both atoms are in excited state at the initial time.
On the basis of the master equation for the density matrix the dynamics of the collective spontaneous radiation of two (Lambda) - type three-level atoms interacting with two mode of quantum electromagnetic field in the damped cavity has been considered. The behavior of the photon numbers in modes and the atomic levels populations has been investigated in the case when only a single atom is excited at the initial time.
On the basis of the master equation for the density matrix the dynamics of the three-level atom interacting with two mode of quantum electromagnetic field in the damped cavity has been considered. The behavior of the mean populations of the atomic levels and photon numbers in modes has been investigated.
The chain of kinetic equations for three-level macroscopic systems intersecting with an electromagnetic field on the basis of then method of elimination of the boson variables is obtained. On its basis the role of two-photon transitions is investigated.
The chain of kinetic equations for two-level and three-level macroscopic systems, interacting with the electromagnetic field, is obtained on the basis of the method of elimination of the boson variables, taking a new type of decoupling for three-particle correlators into account. These equations yield a better description of experimentally observed shape of super-radiant pulse than the standard theories based on the decoupling of the Tyablyakov's type.
The chain of kinetic equations for a three-level extended macroscopic system interacting with an electromagnetic field is obtained on the basis of the method of elimination of the boson variables taking into account the coherent pumping processes. On its basis the conventional superradiance of the system is examined in the markovian limit. The relations between the parameters of the superradiant pulse and those of the pumping pulse of arbitrary duration are obtained. The possibility of description of the triggering superradiance is discussed.
Kinetics of superradiance for a system of two-level emitters interacting with the quantum electromagnetic field is studied. A closed set of equations for atomic correlation functions is obtained which takes into account new decoupling of three- particle correlators. These equations yield a better description of experimentally observed shape of superradiant peak than the standard theories.
Initial conditions corresponding to the stationary evolution of a two-mode two-boson model with interaction between modes and self- action in one of them have been considered. On this basis the possibility of the steady squeezing for both Bose fields has been established. The estimations of the squeezing parameters have been obtained.
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